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91.
K. Zeil M. Baumann E. Beyreuther T. Burris-Mog T. E. Cowan W. Enghardt L. Karsch S. D. Kraft L. Laschinsky J. Metzkes D. Naumburger M. Oppelt C. Richter R. Sauerbrey M. Schürer U. Schramm J. Pawelke 《Applied physics. B, Lasers and optics》2013,110(4):437-444
Proton beams are a promising tool for the improvement of radiotherapy of cancer, and compact laser-driven proton radiation (LDPR) is discussed as an alternative to established large-scale technology facilitating wider clinical use. Yet, clinical use of LDPR requires substantial development in reliable beam generation and transport, but also in dosimetric protocols as well as validation in radiobiological studies. Here, we present the first dose-controlled direct comparison of the radiobiological effectiveness of intense proton pulses from a laser-driven accelerator with conventionally generated continuous proton beams, demonstrating a first milestone in translational research. Controlled dose delivery, precisely online and offline monitored for each out of ~4,000 pulses, resulted in an unprecedented relative dose uncertainty of below 10 %, using approaches scalable to the next translational step toward radiotherapy application. 相似文献
92.
We consider a general method for computing the sum of positive Lyapunov exponents for moderately dense gases. This method is based upon hierarchy techniques used previously to derive the generalized Boltzmann equation for the time-dependent spatial and velocity distribution functions for such systems. We extend the variables in the generalized Boltzmann equation to include a new set of quantities that describe the separation of trajectories in phase space needed for a calculation of the Lyapunov exponents. The method described here is especially suitable for calculating the sum of all of the positive Lyapunov exponents for the system, and may be applied to equilibrium as well as nonequilibrium situations. For low densities we obtain an extended Boltzmann equation, from which, under a simplifying approximation, we recover the sum of positive Lyapunov exponents for hard-disk and hard-sphere systems, obtained before by a simpler method. In addition we indicate how to improve these results by avoiding the simplifying approximation. The restriction to hard-sphere systems in d dimensions is made to keep the somewhat complicated formalism as clear as possible, but the method can be easily generalized to apply to gases of particles that interact with strong short-range forces. (c) 1998 American Institute of Physics. 相似文献
93.
Hutzenthaler Martin Jentzen Arnulf Kruse Thomas 《Foundations of Computational Mathematics》2022,22(4):905-966
Foundations of Computational Mathematics - Partial differential equations (PDEs) are a fundamental tool in the modeling of many real-world phenomena. In a number of such real-world phenomena the... 相似文献
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Michal Swierczewski Dr. Fabrice Cousin Dr. Ewa Banach Dr. Arnulf Rosspeintner Dr. Latevi Max Lawson Daku Dr. Abolfazl Ziarati Dr. Rania Kazan Prof. Gunnar Jeschke Raymond Azoulay Dr. Lay-Theng Lee Prof. Thomas Bürgi 《Angewandte Chemie (International ed. in English)》2023,62(16):e202215746
A bidentate chiral dithiol (diBINAS) is utilised to bridge Au25 nanoclusters to form oligomers. Separation by size allows the isolation of fractions that are stable thanks to the bidentate nature of the linker. The structure of the products is elucidated by small-angle X-ray scattering and calculated using density functional theory. Additional structural details are studied by diffusion-ordered nuclear magnetic resonance spectroscopy, transmission electron microscopy and matrix-assisted laser desorption/ionization time of flight mass spectrometry. Significant changes in the optical properties are analysed by UV/Vis and fluorescence spectroscopies, with the latter demonstrating a strong emission enhancement. Furthermore, the emergent chiral characteristics are studied by circular dichroism. Due to the geometry constraints of the nanocluster assemblies, diBINAS can be regarded as a templating molecule, taking a step towards the directed self-assembly of metal clusters. 相似文献
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Maria Nicolai Alexander Sävert Maria Reuter Michael Schnell Jens Polz Oliver Jäckel Leonhard Karsch Michael Schürer Melanie Oppelt Jörg Pawelke Malte C. Kaluza 《Applied physics. B, Lasers and optics》2014,116(3):643-651
Laser-accelerated electron pulses have been used to irradiate human tumors grown on mice’s ears during radiobiological experiments. These experiments have been carried out with the JETI laser system at the Institute of Optics and Quantum Electronics in Jena, Germany. To treat a total of more than 50 mice, a stable and reliable operation of the laser-electron accelerator with a dose rate exceeding 1 Gy/min was necessary. To achieve this, a sufficient number of electrons at energies in excess of 5 MeV had to be generated. The irradiation time for a single mouse was a few minutes. Furthermore, the particle pulses’ parameters needed to remain achievable for a time period of several weeks. Due to the online detection of the radiation dose, the unavoidable shot-to-shot fluctuations, currently still typical for laser-based particle accelerators, could be compensated. The results demonstrate that particle pulses generated with laser-based accelerators have the potential to be a future alternative for conventional particle accelerators used for the irradiation of tumors. 相似文献
99.
Snehasis Bhunia Rasha Hassanein Arnulf Materny Animesh K. Ojha 《Journal of Raman spectroscopy : JRS》2015,46(12):1191-1199
The interaction of K+ with the zwitterionic form of alanine (ZAla) is investigated using Raman spectroscopy and density functional theory calculations. The Raman spectra of an aqueous solution of Ala and its mixture with KOH at different molar concentrations [ZAla + xKOH, x = 1–5 M] have been recorded in the spectral region 400–1800 cm−1. The wavenumber position of the band at ~529 cm−1 shows a red shift of 14 cm−1, while the Raman band at ~634 cm−1 shows a blue shift of 10 cm−1 with the increasing x from 1 to 5 M. The intensity ratio I634/I529 is increased with increasing x, and it could be because of the increase in concentration of the [ZAla + K+] complex in the solution. The new Raman band appeared at ~1079 cm−1 in the Raman spectra of [ZAla + xKOH, x = 1–5] complex. To determine the most probable site for the interaction of K+ with ZAla, the structures of ZAla and the [ZAla + K+] were optimized at B3LYP/6‐311++G(d,p) level of theory. The electrostatic potential calculation carried out for ZAla reveals that the maximum density of electron is lying over COO−, and therefore, COO− would be the most probable site for the interaction of K+ with ZAla. The theoretically calculated Raman spectra of ZAla, [ZAla + K+] and the [ZAla− + K+] are in good agreement with experimentally observed Raman spectra. Thus, the Raman bands at ~529, 634, and 1079 cm−1 may be used as the Raman fingerprint for the interaction of K+ with COO− of the ZAla and ZAla−. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献